A solid-gas two-phase flow is used to transport powder on an air flow, and in the related art, the powder is separated from the air flow by a particle separator, such as a cyclone separator and a centrifugal separator. Such a particle separator is also used for a solid fuel burner (hereinafter, referred to as “burner”) that burns a powdery low-combustibility fuel in a pulverized coal-fired boiler that uses a low-combustibility fuel, for example, anthracite coal, petroleum coke, biomass, and waste, made in the fine powdery form.
Also, it is anticipated that an air ratio is increased compared to an air-fuel ratio (A/C) in a pulverized coal-fired boiler in the related art during pulverization or at the time of supply depending on a fuel seed, such as biomass. In this case, air unnecessary for combustion has to be separated in the upper stream of the burner and the particle separator is used in this instance, too.
A particle separator 1 shown in FIG. 8A and FIG. 8B as an example in the related art includes a separator main body (hopper) 2 of a circular cylindrical or funnel shape having a circular sectional shape, a gas and solid supply tube 3 for letting a solid-gas two-phase flow stream inside the separator main body 2 from the circumferential direction, an air flow tube 4 provided at the shaft center position in the separator main body 2, and a particle tube 5 provided continuously at the bottom portion of the separator main body 2. In the particle separator 1, a solid-gas two-phase flow streaming inside the separator main body 2 from the circumferential direction flows as a swirling flow that flows in a swirl along the circular cross section. Accordingly, a centrifugal force induced by the swirling flow acts on the solid-gas two-phase flow and solid particles are separated from the air flow. More specifically, the relatively heavy solid particles collide on the wall surface and fall downward by gravity to be collected into the particle tube 5, whereas a relatively light air flow comes out upward from the air flow tube 4 that opens inside the separator main body 2. It should be noted that the separator main body (hopper) 2 is not necessarily shaped to have a circular cross section, and it may be shaped into a cylinder having a rectangular sectional shape or a polygonal sectional shape.
Also, according to another example in the related art shown in FIG. 9A and FIG. 9B, a guide plate 6 protruding toward inside the separator main body 2 from the outlet 3a of the solid and gas supply tube 3 is provided to a main body connecting portion at which the solid and gas supply tube 3 is connected to the separator main body 2. The guide plate 6 is a rectangular plate member provided for guiding the solid-gas two-phase flow streaming inside the separator main body 2 to flow in the wall surface direction, and is therefore capable of improving the collection efficiency of powder particles.
For a powder classifier that separates particles having a particle size larger than a specific particle size from particles included in an air flow and takes out particles having a particle size smaller than the specific particle size together with the air flow, there has been proposed a type including a movable wall body that increases and reduces the sectional area of an inlet channel of a powder-containing gas introducing tube and a movable guide plate that is rotatable about the vertical shaft inside a circular cylindrical body (for example, see Patent Document 1).
[Patent Document 1] Japanese Unexamined Patent Application, Publication No. Hei 5-277444 (see FIG. 1).